This invention relates generally to a door closer, and more particularly to a door closer for automatically moving a door from an open position to a closed position.
A conventional automatic door closer operates by storing energy in a spring mechanism during opening of a door and releasing the stored energy to close the door. Automatic door closers are provided with means for controlling the movement of the door, usually involving hydraulic resistance within the door closer. When the door approaches a fully open or the closed position, a fluid medium within the door closer is caused to flow through restrictive passages which determine the speed of door movement.
A typical automatic door closer generally comprises an elongated housing which may be mounted above the door, in the transom or lintel, or in the floor. A rotating spindle is disposed adjacent one end of the housing such that an end of the spindle extends from the housing for connecting to the door. The portion of the spindle within the housing is connected for rotation with a cam mechanism. During movement of the door from the closed position to an open position, the cam mechanism acts against at least one adjacent roller fixed to a slide assembly for moving the slide assembly longitudinally in the housing. The slide assembly is connected to a piston in a hydraulic dampening arrangement. The piston divides at least a portion of the interior of the housing into two pressure spaces which are connected to each other by one or more passages for the restricted flow of the fluid medium from one space to the other.
In operation, the spindle and the cam mechanism rotate with the door. When the door moves from the closed position to an open position, the cam mechanism abuts against the roller and moves the slide assembly and the piston from a first position towards one end of the housing. This compresses the spring mechanism and the piston forces fluid to flow from one pressure space to the other. The spring mechanism also provides some resistance to the opening of the door to prevent the door from sudden movement. When the door is released, the stored energy of the compressed spring mechanism supplies energy for closing the door. As the door moves back to the closed position, the extending spring mechanism urges the piston and slide assembly to return to the first position causing the roller to act against the cam for rotating the cam mechanism and spindle and moving the door to the closed position. The speed of closing movement is controlled by the passage of fluid from one pressure space to the other caused by the piston.
A problem with door closers of this type includes the immersion of the operative elements of the door closer in hydraulic fluid. The necessary use of fluid seals and other components lend themselves to possible leakage, which constitutes a safety hazard and can have a damaging effect on the door and floor below.
For the foregoing reasons, there is a need for an automatic door closer which minimizes the number of door closer elements immersed in fluid medium and thereby reduces the problem of preventing possible leakage.